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UNITED STATES PATENT O FICE.

BERTHOLD FINKELSTEIN, 0h LINDENAU, SAXON Y, GERMANY.

PROCESS OF MORDANTING.

' SPECIFICATION forming part of Letters Patent No. 352,236, dated November 9,1886.

Application filed March 11, 1886. Serial No 194,818.

To all whom, it may concern/L Be it known that I, BERTHOLD FINKEL- STEIN, of Lindenau, Saxony, Germany, have invented a new and Improved Process of Mordanting Vegetable Textile Fabrics with Antimony Tannate, of which the following specification is a full, clear, and exact description.

The antimony tannate used in dyeing and printing for fixing colors upon vegetable fiber is at present generally prepared byimpreg;

. nating or printing the fabrics with a tannin,

V dants, provided they fulfill certain physical' and placing the same before or after coloring into a solution of tartar emetic, or of potassium antimony oxalate. This method, however, has economical as well as technical disadvantagesas to economy inasmuch as the costly components of the compounds mentioned, the cream of tartar or a large part of the oxalic acid (three molecules of oxalic acid to one atom of antimony,) must be sacrificed in bringing the less valuable component antimony into action. The technical difficulties are, that the acid salts set free from the antimony compounds used accumulate in the bath, that they have a redissolving action on the tannin lakes, and thus cause loss of colors and of mordants. It has been attempted to remove this latter difficulty by adding chalk to the bath; but it was not possible to remove it entirely. That, nevertheless, the above mentioned double salts are exclusively used in the arts for the purpose of antimony mordants is due to the fact that they are the only convenient antimony compounds soluble in water, and that the opinion generally prevails that they alone are capable of giving up their antimony to the tannih'on the fiber. It has been found, however, that insoluble antimony compounds also will act rapidly as morrequirements, principally that they are capable of ready reaction, and that they are in a state of very fine division. Freshly-precipi tated antimony oxide would answer under certain circumstances, and favorable results in this respect have lately been published. It has, however, the disturbing quality of not being able to remain long in the desirable amorphous condition, but to become crystalline through the whole mass after a shorter (No specimens.)

or longer timesometiines instantaneously,

wherebyit loses the mechanical as well as the chemical properties required for its use as a mordant.

The oxalate of antimony, which contains to one atom of antimony one molecule of oxalic acid, behaves quite differently. It forms an exceedingly fine powder, which the microscope shows to consist of the most fine needleshaped crystals. It is not decomposed by water, but when stirred with water it remains suspended, forming a milky liquid, which is clarified but slowly. It is very sensitive to chemical influences, and gives up its antimony with the greatest readiness, for which reason it behaves to gallic acid or to fabrics impregnated with gallic acid in the same manner as if it were in solution.

The advantage which this compound offers over the other abovementioned antimony mordants is evident. It notonly cheapens the mordant by the cost of the large quantity of expensive acids required in the other case, but it also does not load the bath with such a large quantity of acid alkali salts of organic acids, which, owing to their disposition to form double salts with antimony, prevent a perfect utilization of the tannin. The

oxalic acid,which in this case also is liberated.

by the process of mordanting, may easily be entirely eliminated during .or after mordanting by chalk or other well-known means for neutralization. For this reason I employ the above-described antimony oxalate for mordanting vegetable fibers, yarns, or woven goods printed or impregnated with tannin, in place .of other soluble antimony compounds commonly used, or of freshly-precipitated antimony oxide, and I proceed in this as follows: The fabrics, yarns, &c., impregnated orprinted with tannin are, before or after coloring, placed into a water-bath, wherein the oxalate of antimony is maintained in suspension by stirring. During this part of the operation I raise the temperature of the bath to 63 Reaumur, and more, and in case the liberated acid should be liable to affect the color to be produced I add a neutralizing substance-such as chalk, '&c.- before or during mordanting; or I afterward treat the mordantedgoods with pure water, or wit-ha neutralizing medium, or a solution of soap, for removing the adhering oxalic acid, In testimony whereof I have signed my respectively, for rendering it innoxious. name to this specification in the presence of 10 I claim as my inventiontwo subscribing witnesses.

Mordanting vegetable fibers, yarns, and

5 Woven gocds impregnated or printed with BERTHOLD FINKELSTEIN' tannin with antimony, by treating the same Witnesses: with antimony oxalate suspended in water, EDMUND EACH, substantially as specified. RICHARD N URNBERGEIR. 

